This invention relates to the preparation of 1-chloro-2,2-difluoroethane (142) from 1,2-dichloroethene ("1130"), particularly to processes wherein said 1130 is fluorinated with hydrogen fluoride ("HF") in the gas phase in the presence of a fluorinated metal salt. 1-Chloro-2,2-difluoroethane is known to have utility as a foam blowing agent.
A. L. Henne et al, in the Journal of the American Chemical Society, Vol. 70, pages 758-760 (1948), reported that reacting 1130 with HF in the presence of a boron trifluoride catalyst yielded 1,2-dichloro-2-fluoroethane. That is, they were able to add HF to the double bond of 1130, but could not substitute F for Cl so as to form 142. Since 142 is useful as a low ozone depleting blowing agent, it would be useful to have a process for readily preparing the same.